I would like to make a simple tile on the Microsoft Band 2 that can display the current skin temperature when the user clicks on the tile. One way to do this is to register a listener for BandSkinTemperatureEvent and constantly save the temperature, and ACTION_TILE_OPENED to detect the user click, then update the temperature back to the tile using TextBlockData. But that seems like an extremely roundabout way to display a sensor reading which essentially should already be available on the Band itself. Also, this won't work when the Android phone is not connected.
Is there a way to achieve this functionality without having to use the above method?
Short answer: No.
Longer answer: If you look at the specs of either Microsoft Band, they don't have much memory, and certainly not enough to allow the running of foreign code. So, in order to allow what you are asking for, they would need to create a new layout object. And, given that the skin temperature sensor is too close to the band's processor to ever actually be accurate, the chances of them doing that is almost zero.